Structural Health Monitoring by some form of semi-automated process has been near the top of the engineers 'wish list' for many ears in order to monitor the performance of fatigue loaded structures. Many attempts have been made mainly by attempting to assess the actual load spectrum applied to the structure during service and appropriate fatigue analyses based on the results. While limited success can be claimed for this approach it usually has a weakness in that vital information may be lost in the event of electrical power being lost to the system. During the period of inactivity it is possible, for instance, to miss the 'hundred year wave or gust' as well as small events that would be incomplete and therefore inaccurate assessment of fatigue loading history. An entirely new approach is described in this paper that is insensitive to los of electrical power based on a 'modified acoustic emission' principle. Experimental mechanics procedures have led to a much more direct identification of fatigue testing of Aircraft Structures and then to develop it into a flying Aircraft Health and Usage Monitoring System.
Eddie W. O'Brien,
"Experimental mechanics for structural health monitoring", Proc. SPIE 4537, Third International Conference on Experimental Mechanics, (29 May 2002); doi: 10.1117/12.468834; https://doi.org/10.1117/12.468834